Ubiquinone is a benzoquinone derivative distributed broadly in the living world. Ubiquinone is localized in mitochondria, lysosomes, Golgi bodies, microsomes, peroxisomes, cell membranes, etc., are substances indispensable for the maintenance of biological functions as constituents of the electron transport system, and are known to be involved in activation of ATP production, antioxidant activity in the living body, and membrane stabilization. Since ubiquinone is not only supplied from diets but also biosynthesized in the body, it might be considered that the necessary amount of ubiquinone is available in the normal state but it is known that actually the ubiquinone content in the body is markedly decreased due to aging and various stresses to which the living body is subjected.
For example, it is reported that whereas the ubiquinone content in the human heart in the 19 to 21 years of age is 110.0 μg/g, the content is drastically reduced to less than one-half, namely 47.2 μg/g, in the 77 to 81 years of age [Kalen, A. et al., Lipids, 24, 579-584 (1989)]. Moreover, the ubiquinone content in plasma is decreased in uremic patients, patients under chronic hemodialysis treatment, and patients with various allergic diseases as compared with healthy persons [Triolo, L., Nephron, 66, 153-156 (1994); Folkers, K., BioFactors, 1, 303-306 (1988)]. In patients with hyperlipemia, the ubiquinone content in the LDL cholesterol fraction is decreased [Kontush, A., et al., Atherosclerosis, 129, 119-126 (1997)]. Furthermore, it has been pointed out that administration of cholesterol synthesis inhibitors which are in common use today as therapeutic drugs for hypercholesterolemia inhibits the biosynthesis of ubiquinone as well, causing depressions in ubiquinone concentration in tissues [E. L. Appelkvist et al., Clinical Investigator, 71, S97-S102 (1993)]. In addition, decreases in the tissue concentration are suspected under conditions favoring production of peroxides in the living body, such as strenuous exercises or overfatigue. Decreases in the ubiquinone content in the body characteristically lead to depressions in ATP productivity and cardiac function, decreased resistance to oxidation stress, and instability of the biomembranes, thus being deleterious to health.
To make up for a shortage of ubiquinone is instrumental for promoting energy production in mitochondria, enhancing the antioxidant capacity of the living body, and maintenance of homeostasis. In fact, elevation of the cardiac function due to administration of ubiquinone has been reported [Kishi, T. et al., Clin. Investg., 71, S71-S75 (1993)]; ameliorating efficacy in cardiac diseases such as congestive heart failure, angina pectoris, myocardial infarction, etc. by ubiquinone [Singh, R. B. et al., Inter. J. Cardiology, 68, 23-29 (1999), Singh, R. B. et al., Cardiovasc. Drugs Ther., 12, 347-353 (1998)]; preventive and ameliorative efficacy in atherosclerosis, hypertension, diabetes, neoplastic diseases, periodontal diseases, and allergies [Singh, R B. et al., Atherosclerosis, 148, 275-282 (1999), Digiesi, V., et al., Curr. Therap. Res., 51, 668-672 (1992), Kishi, T., et al., Journal of Dental Health, 43, 667-672 (1993), Shimura Y., et al., Rinsho-to-Kenkyu, 58, 1349-1352 (1981)]; reproductive performance-improving effect, inhibition of oxidation of LDL cholesterol, dialysis frequency-reducing effect in renal dialysis patients, nonspecific immunity-potentiating effect, and the like are known [Stocker et al., Mol. Aspects Med., 18, S85-S103 (1997), Lippa, S., Mol. Aspects Med., 15, S213-S219 (1994)]. Furthermore, ubiquinone is already in use clinically as a therapeutic drug for the palpitation, short breadth, and anasarca arising from congestive heart failure or mild heart diseases.
As means for supplying the ubiquinone which tend to become decreased and fall short of the requirements due to aging and stresses despite their being indispensable for the maintenance of biological functions as mentioned above, it has already been practiced to supply this substance as a drug or as a food supplement in the form of tablets or capsules but for healthy or semi-healthy persons in whom deficiencies are slight and unqualified for medical care, and the like persons, it is more convenient to take this substance in the same ways as the ordinary food than taking it in the form of tablets or capsules. Furthermore, in the case of foods, it is possible to produce foods having various flavors and forms, thus offering the great advantage that the consumer may ingest the food repeatedly without being bored.
Ubiquinone is known to occur broadly in many ordinary foodstuffs of the animal or vegetable origin, such as meats, fish meats, cereals, vegetables, fruits, dairy products, and eggs, the content is generally low except in beef in which it is as high 30 μg/g, and the like. For example, the said content is as low as about 1.5 μg/g in hen's eggs, about 1.1 μg/g in wheat breads, and about 0.52 μg/g in potatoes, so that the daily ingestion from the usual diets is about 3 to 5 mg. Furthermore, the absorption rate of ubiquinone after oral ingestion is low, so that with the ordinary foods taken in the usual manner, it is not easy to sufficiently supply ubiquinone in the living body which is liable to be decreased due to various stresses.
In such cases, if a ubiquinone-enriched food is available, improvements in its absorption rate could be expected from the interaction with the food component and, hence, it can be considered that ubiquinone, which is liable to be fall short of the requirements, can be supplied with ease. However, partly because ubiquinone had been classified as a drug with the use thereof as food being restricted in Japan, only a few ubiquinone-enriched foods are available today. The only exceptions are Japanese Kokai Publication Hei-03-167293 “the method of preventing oxidation of oils/fats and oil/fat-containing foods”, Japanese Kokai Publication 2000-197445 “Freshness-keeping agent for animal meats, fish meats, and processed foods thereof”, Japanese Kokai Publication Hei-10-45614 “Foods for diet therapy and pharmaceutical products for inhibiting blood coagulation”, and Japanese Kohyo Publication 2001-504343 “Ubiquinone-containing non-alcoholic beverages”. Disclosed in Japanese Kokai Publication Hei-03-167293 relates to a technology for preventing oxidation of oils/fats which comprises concurrent admixing of ubiquinone, ascorbic acid, and a natural emulsifier, but there is no disclosure of the concept of a ubiquinone-enriched food for supplementation use. Japanese Kokai Publication 2000-197445 is concerned with the use of ubiquinone as a freshness-keeping agent for animal meats, fish meats, and processed foods thereof and the level of addition is so low that substantially no supplementation effect can be expected. Disclosed in Japanese Kokai Publication Hei-10-45614 is a food for diet therapy for inhibiting blood coagulation which comprises using a ubiquinone-rich corn germ oil, but its ubiquinone content is only about 0.0007 to 0.0008% by weight (hereinafter referred to briefly as %), thus is insufficient to meet the requirements for making up for deficiencies in ubiquinone. Moreover, this technology is concerned with utilization of the ubiquinone occurring inherently in corn germ oil, and does not describe the concept of enrichment with ubiquinone. Japanese Kohyo Publication 2001-504343 discloses a technology of solubilizing ubiquinone with polyoxyethylene sorbitan monooleate but the use of such a nonionic surfactant has the risk for causing hemolysis, mucosal irritation, mucosal defect and the like and, in many cases, utilization thereof in food applications is actually hesitated.
Under such circumstance, as the food which can supply ubiquinone, a substance indispensable to the living body but liable to be decreased and fall short of requirements due to aging and stresses, one may reasonably contemplates a food sufficiently enriched with ubiquinone, improved in absorption rate, and having a pleasing flavor.